increased version number before creating a new release
[mod_auth_kerb.git] / src / mod_auth_kerb.c
index 8dc172f..97b4761 100644 (file)
@@ -1,5 +1,79 @@
+/*
+ * Daniel Kouril <kouril@users.sourceforge.net>
+ *
+ * Source and Documentation can be found at:
+ * http://modauthkerb.sourceforge.net/
+ *
+ * Based on work by
+ *   James E. Robinson, III <james@ncstate.net>
+ *   Daniel Henninger <daniel@ncsu.edu>
+ *   Ludek Sulak <xsulak@fi.muni.cz>
+ */
+
+/* ====================================================================
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2000-2003 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Apache" and "Apache Software Foundation" must
+ *    not be used to endorse or promote products derived from this
+ *    software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache",
+ *    nor may "Apache" appear in their name, without prior written
+ *    permission of the Apache Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ * Portions of this software are based upon public domain software
+ * originally written at the National Center for Supercomputing Applications,
+ * University of Illinois, Urbana-Champaign.
+ */
+
 #ident "$Id$"
 
+#include "config.h"
+
+#define MODAUTHKERB_VERSION "5.0-rc3"
+
 #ifndef APXS1
 #include "ap_compat.h"
 #include "apr_strings.h"
 
 #ifdef KRB5
 #include <krb5.h>
-#include <gssapi.h>
-#ifndef HEIMDAL
-#include <gssapi_generic.h>
-#define GSS_C_NT_USER_NAME gss_nt_user_name
-#define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
-#define krb5_get_err_text(context,code) error_message(code)
+#ifdef HEIMDAL
+#  include <gssapi.h>
+#else
+#  include <gssapi/gssapi.h>
+#  include <gssapi/gssapi_generic.h>
+#  define GSS_C_NT_USER_NAME gss_nt_user_name
+#  define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
+#  define krb5_get_err_text(context,code) error_message(code)
 #endif
+#include "spnegokrb5.h"
 #endif /* KRB5 */
 
 #ifdef KRB4
+/*Prevent warning about closesocket redefinition (Apache's ap_config.h and 
+ * MIT Kerberos' port-sockets.h both define it as close) */
+#ifdef closesocket
+#  undef closesocket
+#endif
 #include <krb.h>
+#include <netdb.h> /* gethostbyname() */
 #endif /* KRB4 */
 
 #ifdef APXS1
@@ -38,21 +121,13 @@ module AP_MODULE_DECLARE_DATA auth_kerb_module;
 #ifdef APXS1
 #define MK_POOL pool
 #define MK_TABLE_GET ap_table_get
-#define MK_TABLE_SET ap_table_set
-#define MK_TABLE_TYPE table
-#define MK_PSTRDUP ap_pstrdup
 #define MK_USER r->connection->user
 #define MK_AUTH_TYPE r->connection->ap_auth_type
-#define MK_ARRAY_HEADER array_header
 #else
 #define MK_POOL apr_pool_t
 #define MK_TABLE_GET apr_table_get
-#define MK_TABLE_SET apr_table_set
-#define MK_TABLE_TYPE apr_table_t
-#define MK_PSTRDUP apr_pstrdup
 #define MK_USER r->user
 #define MK_AUTH_TYPE r->ap_auth_type
-#define MK_ARRAY_HEADER apr_array_header_t
 #endif /* APXS1 */
 
 
@@ -61,9 +136,10 @@ module AP_MODULE_DECLARE_DATA auth_kerb_module;
  ***************************************************************************/
 typedef struct {
        char *krb_auth_realms;
-       char *krb_force_instance;
        int krb_save_credentials;
-       char *service_name;
+       int krb_verify_kdc;
+       char *krb_service_name;
+       int krb_authoritative;
 #ifdef KRB5
        char *krb_5_keytab;
        int krb_method_gssapi;
@@ -100,8 +176,14 @@ static const command_rec kerb_auth_cmds[] = {
    command("KrbSaveCredentials", ap_set_flag_slot, krb_save_credentials,
      FLAG, "Save and store credentials/tickets retrieved during auth."),
 
-   command("KrbServiceName", ap_set_string_slot, service_name,
-     TAKE1, "Kerberos service name to be used by apache."),
+   command("KrbVerifyKDC", ap_set_flag_slot, krb_verify_kdc,
+     FLAG, "Verify tickets against keytab to prevent KDC spoofing attacks."),
+
+   command("KrbServiceName", ap_set_string_slot, krb_service_name,
+     TAKE1, "Service name to be used by Apache for authentication."),
+
+   command("KrbAuthoritative", ap_set_flag_slot, krb_authoritative,
+     FLAG, "Set to 'off' to allow access control to be passed along to lower modules if the UserID is not known to this module."),
 
 #ifdef KRB5
    command("Krb5Keytab", ap_set_file_slot, krb_5_keytab,
@@ -143,6 +225,9 @@ static void *kerb_dir_create_config(MK_POOL *p, char *d)
        kerb_auth_config *rec;
 
        rec = (kerb_auth_config *) ap_pcalloc(p, sizeof(kerb_auth_config));
+        ((kerb_auth_config *)rec)->krb_verify_kdc = 1;
+       ((kerb_auth_config *)rec)->krb_service_name = "khttp";
+       ((kerb_auth_config *)rec)->krb_authoritative = 1;
 #ifdef KRB5
        ((kerb_auth_config *)rec)->krb_method_k5pass = 1;
        ((kerb_auth_config *)rec)->krb_method_gssapi = 1;
@@ -164,16 +249,23 @@ void log_rerror(const char *file, int line, int level, int status,
                 const request_rec *r, const char *fmt, ...)
 {
    char errstr[1024];
+   char errnostr[1024];
    va_list ap;
 
    va_start(ap, fmt);
    vsnprintf(errstr, sizeof(errstr), fmt, ap);
    va_end(ap);
 
+   errnostr[0] = '\0';
+   if (errno)
+      snprintf(errnostr, sizeof(errnostr), "%s: (%s)", errstr, strerror(errno));
+   else
+      snprintf(errnostr, sizeof(errnostr), "%s", errstr);
+   
 #ifdef APXS1
-   ap_log_rerror(file, line, level, r, "%s", errstr);
+   ap_log_rerror(file, line, level | APLOG_NOERRNO, r, "%s", errnostr);
 #else
-   ap_log_rerror(file, line, level, status, r, "%s", errstr);
+   ap_log_rerror(file, line, level | APLOG_NOERRNO, status, r, "%s", errnostr);
 #endif
 }
 
@@ -182,6 +274,67 @@ void log_rerror(const char *file, int line, int level, int status,
  Username/Password Validation for Krb4
  ***************************************************************************/
 static int
+verify_krb4_user(request_rec *r, char *name, char *instance, char *realm,
+                char *password, char *linstance, char *srvtab, int krb_verify_kdc)
+{
+   int ret;
+   char *phost;
+   unsigned long addr;
+   struct hostent *hp;
+   const char *hostname;
+   KTEXT_ST ticket;
+   AUTH_DAT authdata;
+   char lrealm[REALM_SZ];
+
+   ret = krb_get_pw_in_tkt(name, instance, realm, "krbtgt", realm, 
+                          DEFAULT_TKT_LIFE, password);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot get krb4 ticket: krb_get_pw_in_tkt() failed: %s",
+                krb_get_err_text(ret));
+      return ret;
+   }
+
+   if (!krb_verify_kdc)
+      return ret;
+
+   hostname = ap_get_server_name(r);
+
+   hp = gethostbyname(hostname);
+   if (hp == NULL) {
+      dest_tkt();
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot verify krb4 ticket: gethostbyname() failed: %s",
+                hstrerror(h_errno));
+      return h_errno;
+   }
+   memcpy(&addr, hp->h_addr, sizeof(addr));
+
+   phost = krb_get_phost((char *)hostname);
+
+   krb_get_lrealm(lrealm, 1);
+
+   ret = krb_mk_req(&ticket, linstance, phost, lrealm, 0);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot verify krb4 ticket: krb_mk_req() failed: %s",
+                krb_get_err_text(ret));
+      dest_tkt();
+      return ret;
+   }
+
+   ret = krb_rd_req(&ticket, linstance, phost, addr, &authdata, srvtab);
+   if (ret) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "Cannot verify krb4 ticket: krb_rd_req() failed: %s",
+                krb_get_err_text(ret));
+      dest_tkt();
+   }
+
+   return ret;
+}
+
+static int
 krb4_cache_cleanup(void *data)
 {
    char *tkt_file = (char *) data;
@@ -199,16 +352,30 @@ authenticate_user_krb4pwd(request_rec *r,
    int ret;
    const char *sent_pw;
    const char *sent_name;
+   char *sent_instance;
    char tkt_file[32];
    char *tkt_file_p = NULL;
    int fd;
    const char *realms;
    const char *realm;
-   krb_principal pr;
+   char *user;
+   char lrealm[REALM_SZ];
+   int all_principals_unkown;
 
    sent_pw = ap_pbase64decode(r->pool, auth_line);
    sent_name = ap_getword (r->pool, &sent_pw, ':');
 
+   /* do not allow user to override realm setting of server */
+   if (strchr(sent_name, '@')) {
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+                "specifying realm in user name is prohibited");
+      return HTTP_UNAUTHORIZED;
+   }
+
+   sent_instance = strchr(sent_name, '.');
+   if (sent_instance)
+      *sent_instance++ = '\0'; 
+
    snprintf(tkt_file, sizeof(tkt_file), "/tmp/apache_tkt_XXXXXX");
    fd = mkstemp(tkt_file);
    if (fd < 0) {
@@ -224,40 +391,57 @@ authenticate_user_krb4pwd(request_rec *r,
 
    krb_set_tkt_string(tkt_file);
 
+   all_principals_unkown = 1;
    realms = conf->krb_auth_realms;
    do {
+      memset(lrealm, 0, sizeof(lrealm));
       realm = NULL;
       if (realms)
         realm = ap_getword_white(r->pool, &realms);
 
-      ret = krb_verify_user_srvtab((char *)sent_name, "", (char *)realm,
-                                  (char *)sent_pw, 1, "khttp",
-                                  conf->krb_4_srvtab);
+      if (realm == NULL) {
+        ret = krb_get_lrealm(lrealm, 1);
+        realm = lrealm;
+      }
+      if (realm == NULL || *realm == '\0')
+        break;
+
+      ret = verify_krb4_user(r, (char *)sent_name, 
+                            (sent_instance) ? sent_instance : "",
+                            (char *)realm, (char *)sent_pw,
+                            conf->krb_service_name,
+                            conf->krb_4_srvtab, conf->krb_verify_kdc);
+      if (!conf->krb_authoritative && ret) {
+        /* if we're not authoritative, we allow authentication to pass on
+         * to another modules if (and only if) the user is not known to us */
+        if (all_principals_unkown && ret != KDC_PR_UNKNOWN)
+           all_principals_unkown = 0;
+      }
+
       if (ret == 0)
         break;
    } while (realms && *realms);
 
    if (ret) {
-      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "Verifying krb4 password failed (%d)", ret);
-      ret = HTTP_UNAUTHORIZED;
+      /* XXX log only in the verify_krb4_user() call */
+      log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "Verifying krb4 password failed");
+      ret = (!conf->krb_authoritative && all_principals_unkown == 1 && ret == KDC_PR_UNKNOWN) ?
+                DECLINED : HTTP_UNAUTHORIZED;
       goto end;
    }
 
-   if ((ret = krb_get_tf_realm(tkt_file, pr.realm)) ||
-       (ret = tf_init(tkt_file, R_TKT_FIL)) ||
-       (ret = tf_get_pname(pr.name)) ||
-       (ret = tf_get_pinst(pr.instance))) {
-      log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
-                "Cannot read krb4 principal from tfile (%d)", ret);
-      ret = HTTP_INTERNAL_SERVER_ERROR;
-      goto end;
-   }
+   user = ap_pstrdup(r->pool, sent_name);
+   if (sent_instance)
+      user = ap_pstrcat(r->pool, user, ".", sent_instance, NULL);
+   user = ap_pstrcat(r->pool, user, "@", realm, NULL);
 
-   MK_USER = ap_pstrdup (r->pool, krb_unparse_name(&pr));
+   MK_USER = user;
    MK_AUTH_TYPE = "Basic";
    ap_table_setn(r->subprocess_env, "KRBTKFILE", tkt_file_p);
 
+   if (!conf->krb_save_credentials)
+      krb4_cache_cleanup(tkt_file);
+
 end:
    if (ret)
       krb4_cache_cleanup(tkt_file);
@@ -272,11 +456,11 @@ end:
 /*************************************************************************** 
  Username/Password Validation for Krb5
  ***************************************************************************/
-#ifndef HEIMDAL
-krb5_error_code
-krb5_verify_user(krb5_context context, krb5_principal principal,
-                krb5_ccache ccache, const char *password, krb5_boolean secure,
-                const char *service)
+/* Inspired by krb5_verify_user from Heimdal */
+static krb5_error_code
+verify_krb5_user(request_rec *r, krb5_context context, krb5_principal principal,
+                krb5_ccache ccache, const char *password, const char *service,
+                krb5_keytab keytab, int krb_verify_kdc)
 {
    krb5_creds creds;
    krb5_principal server = NULL;
@@ -291,15 +475,15 @@ krb5_verify_user(krb5_context context, krb5_principal principal,
    if (ret)
       return ret;
 
-   ret = krb5_sname_to_principal(context, NULL, service, 
+   ret = krb5_sname_to_principal(context, ap_get_server_name(r), service, 
                                 KRB5_NT_SRV_HST, &server);
    if (ret)
       goto end;
 
    krb5_verify_init_creds_opt_init(&opt);
-   krb5_verify_init_creds_opt_set_ap_req_nofail(&opt, secure);
+   krb5_verify_init_creds_opt_set_ap_req_nofail(&opt, krb_verify_kdc);
 
-   ret = krb5_verify_init_creds(context, &creds, server, NULL, NULL, &opt);
+   ret = krb5_verify_init_creds(context, &creds, server, keytab, NULL, &opt);
    if (ret)
       goto end;
 
@@ -315,8 +499,6 @@ end:
       krb5_free_principal(context, server);
    return ret;
 }
-#endif
-
 
 static int
 krb5_cache_cleanup(void *data)
@@ -357,9 +539,11 @@ create_krb5_ccache(krb5_context kcontext,
    int ret;
    krb5_ccache tmp_ccache = NULL;
 
-#ifdef HEIMDAL
+#ifdef HAVE_KRB5_CC_GEN_NEW
    problem = krb5_cc_gen_new(kcontext, &krb5_fcc_ops, &tmp_ccache);
 #else
+   /* only older MIT seem to not have the krb5_cc_gen_new() call, so we use
+    * MIT specific call here */
    problem = krb5_fcc_generate_new(kcontext, &tmp_ccache);
    /* krb5_fcc_generate_new() doesn't set KRB5_TC_OPENCLOSE, which makes 
       krb5_cc_initialize() fail */
@@ -450,13 +634,14 @@ int authenticate_user_krb5pwd(request_rec *r,
    const char      *sent_pw = NULL; 
    const char      *sent_name = NULL;
    const char      *realms = NULL;
-   const char     *service_name = NULL;
    krb5_context    kcontext = NULL;
    krb5_error_code code;
    krb5_principal  client = NULL;
    krb5_ccache     ccache = NULL;
+   krb5_keytab     keytab = NULL;
    int             ret;
-   char *name = NULL;
+   char            *name = NULL;
+   int             all_principals_unkown;
 
    code = krb5_init_context(&kcontext);
    if (code) {
@@ -475,9 +660,11 @@ int authenticate_user_krb5pwd(request_rec *r,
       goto end;
    } 
 
-#ifdef HEIMDAL
+#ifdef HAVE_KRB5_CC_GEN_NEW
    code = krb5_cc_gen_new(kcontext, &krb5_mcc_ops, &ccache);
 #else
+   /* only older MIT seem to not have the krb5_cc_gen_new() call, so we use
+    * MIT specific call here */
    code = krb5_mcc_generate_new(kcontext, &ccache);
 #endif
    if (code) {
@@ -489,17 +676,9 @@ int authenticate_user_krb5pwd(request_rec *r,
    }
 
    if (conf->krb_5_keytab)
-      setenv("KRB5_KTNAME", conf->krb_5_keytab, 1);
-      /* kcontext->default_keytab = conf->krb_5_keytab; */
-
-   if (conf->service_name) {
-      char *p;
-      service_name = ap_pstrdup(r->pool, conf->service_name);
-      if ((p=strchr(service_name, '/')))
-        *p = '\0';
-   } else
-      service_name = "khttp";
+      krb5_kt_resolve(kcontext, conf->krb_5_keytab, &keytab);
 
+   all_principals_unkown = 1;
    realms = conf->krb_auth_realms;
    do {
       if (realms && (code = krb5_set_default_realm(kcontext,
@@ -514,8 +693,16 @@ int authenticate_user_krb5pwd(request_rec *r,
       if (code)
         continue;
 
-      code = krb5_verify_user(kcontext, client, ccache, sent_pw, 1, 
-                             service_name);
+      code = verify_krb5_user(r, kcontext, client, ccache, sent_pw, 
+                             conf->krb_service_name, 
+                             keytab, conf->krb_verify_kdc);
+      if (!conf->krb_authoritative && code) {
+        /* if we're not authoritative, we allow authentication to pass on
+         * to another modules if (and only if) the user is not known to us */
+        if (all_principals_unkown && code != KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN)
+           all_principals_unkown = 0;
+      }
+
       if (code == 0)
         break;
 
@@ -526,10 +713,15 @@ int authenticate_user_krb5pwd(request_rec *r,
    memset((char *)sent_pw, 0, strlen(sent_pw));
 
    if (code) {
+      /* XXX log only in the verify_krb5_user() call */
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                 "Verifying krb5 password failed: %s",
                 krb5_get_err_text(kcontext, code));
-      ret = HTTP_UNAUTHORIZED;
+      if (!conf->krb_authoritative && all_principals_unkown == 1 && code == KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN)
+        ret = DECLINED;
+      else
+        ret = HTTP_UNAUTHORIZED;
+
       goto end;
    }
 
@@ -554,6 +746,8 @@ end:
       krb5_free_principal(kcontext, client);
    if (ccache)
       krb5_cc_destroy(kcontext, ccache);
+   if (keytab)
+      krb5_kt_close(kcontext, keytab);
    krb5_free_context(kcontext);
 
    return ret;
@@ -670,18 +864,15 @@ get_gss_creds(request_rec *r,
    gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
    OM_uint32 major_status, minor_status, minor_status2;
    gss_name_t server_name = GSS_C_NO_NAME;
+   char buf[1024];
+
+   snprintf(buf, sizeof(buf), "%s/%s", conf->krb_service_name, ap_get_server_name(r));
+
+   input_token.value = buf;
+   input_token.length = strlen(buf) + 1;
 
-   if (conf->service_name) {
-      input_token.value = conf->service_name;
-      input_token.length = strlen(conf->service_name) + 1;
-   }
-   else {
-      input_token.value = "khttp";
-      input_token.length = 6;
-   }
    major_status = gss_import_name(&minor_status, &input_token,
-                                 (conf->service_name) ? 
-                                      GSS_C_NT_USER_NAME : GSS_C_NT_HOSTBASED_SERVICE,
+                                 GSS_C_NT_USER_NAME,
                                  &server_name);
    if (GSS_ERROR(major_status)) {
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
@@ -705,6 +896,33 @@ get_gss_creds(request_rec *r,
 }
 
 static int
+cmp_gss_type(gss_buffer_t token, gss_OID oid)
+{
+   unsigned char *p;
+   size_t len;
+
+   if (token->length == 0)
+      return GSS_S_DEFECTIVE_TOKEN;
+
+   p = token->value;
+   if (*p++ != 0x60)
+      return GSS_S_DEFECTIVE_TOKEN;
+   len = *p++;
+   if (len & 0x80) {
+      if ((len & 0x7f) > 4)
+        return GSS_S_DEFECTIVE_TOKEN;
+      p += len & 0x7f;
+   }
+   if (*p++ != 0x06)
+      return GSS_S_DEFECTIVE_TOKEN;
+
+   if (((OM_uint32) *p++) != oid->length)
+      return GSS_S_DEFECTIVE_TOKEN;
+
+   return memcmp(p, oid->elements, oid->length);
+}
+
+static int
 authenticate_user_gss(request_rec *r,
                      kerb_auth_config *conf,
                      const char *auth_line)
@@ -716,12 +934,11 @@ authenticate_user_gss(request_rec *r,
   int ret;
   gss_name_t client_name = GSS_C_NO_NAME;
   gss_cred_id_t delegated_cred = GSS_C_NO_CREDENTIAL;
-  static int initial_return = HTTP_UNAUTHORIZED;
+  OM_uint32 (*accept_sec_token)();
+  gss_OID_desc spnego_oid;
 
-  /* needed to work around replay caches */
-  if (!ap_is_initial_req(r))
-     return initial_return;
-  initial_return = HTTP_UNAUTHORIZED;
+  spnego_oid.length = 6;
+  spnego_oid.elements = (void *)"\x2b\x06\x01\x05\x05\x02";
 
   if (gss_connection == NULL) {
      gss_connection = ap_pcalloc(r->connection->pool, sizeof(*gss_connection));
@@ -735,8 +952,20 @@ authenticate_user_gss(request_rec *r,
      ap_register_cleanup(r->connection->pool, gss_connection, cleanup_gss_connection, ap_null_cleanup);
   }
 
-  if (conf->krb_5_keytab)
-     setenv("KRB5_KTNAME", conf->krb_5_keytab, 1);
+  if (conf->krb_5_keytab) {
+     char *ktname;
+     /* we don't use the ap_* calls here, since the string passed to putenv()
+      * will become part of the enviroment and shouldn't be free()ed by apache
+      */
+     ktname = malloc(strlen("KRB5_KTNAME=") + strlen(conf->krb_5_keytab) + 1);
+     if (ktname == NULL) {
+       log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "malloc() failed: not enough memory");
+       ret = HTTP_INTERNAL_SERVER_ERROR;
+       goto end;
+     }
+     sprintf(ktname, "KRB5_KTNAME=%s", conf->krb_5_keytab);
+     putenv(ktname);
+  }
 
   if (gss_connection->server_creds == GSS_C_NO_CREDENTIAL) {
      ret = get_gss_creds(r, conf, &gss_connection->server_creds);
@@ -763,17 +992,20 @@ authenticate_user_gss(request_rec *r,
   }
   input_token.length = ap_base64decode(input_token.value, auth_param);
 
-  major_status = gss_accept_sec_context(&minor_status,
-                                       &gss_connection->context,
-                                       gss_connection->server_creds,
-                                       &input_token,
-                                       GSS_C_NO_CHANNEL_BINDINGS,
-                                       &client_name,
-                                       NULL,
-                                       &output_token,
-                                       NULL,
-                                       NULL,
-                                       &delegated_cred);
+  accept_sec_token = (cmp_gss_type(&input_token, &spnego_oid) == 0) ?
+                       gss_accept_sec_context_spnego : gss_accept_sec_context;
+
+  major_status = accept_sec_token(&minor_status,
+                                 &gss_connection->context,
+                                 gss_connection->server_creds,
+                                 &input_token,
+                                 GSS_C_NO_CHANNEL_BINDINGS,
+                                 &client_name,
+                                 NULL,
+                                 &output_token,
+                                 NULL,
+                                 NULL,
+                                 &delegated_cred);
   if (output_token.length) {
      char *token = NULL;
      size_t len;
@@ -790,7 +1022,7 @@ authenticate_user_gss(request_rec *r,
      ap_base64encode(token, output_token.value, output_token.length);
      token[len] = '\0';
      ap_table_set(r->err_headers_out, "WWW-Authenticate",
-                 ap_pstrcat(r->pool, "GSS-Negotiate ", token, NULL));
+                 ap_pstrcat(r->pool, "Negotiate ", token, NULL));
      gss_release_buffer(&minor_status2, &output_token);
   }
 
@@ -827,27 +1059,6 @@ authenticate_user_gss(request_rec *r,
 
   gss_release_buffer(&minor_status, &output_token);
 
-#if 0
-  /* If the user comes from a realm specified by configuration don't include
-      its realm name in the username so that the authorization routine could
-      work for both Password-based and Ticket-based authentication. It's
-      administrators responsibility to include only such realm that have
-      unified principal instances, i.e. if the same principal name occures in
-      multiple realms, it must be always assigned to a single user.
-  */    
-  p = strchr(r->connection->user, '@');
-  if (p != NULL) {
-     const char *realms = conf->gss_krb5_realms;
-
-     while (realms && *realms) {
-       if (strcmp(p+1, ap_getword_white(r->pool, &realms)) == 0) {
-          *p = '\0';
-          break;
-       }
-     }
-  }
-#endif
-
   ret = OK;
 
 end:
@@ -862,11 +1073,20 @@ end:
 
   cleanup_gss_connection(gss_connection);
 
-  initial_return = ret;
   return ret;
 }
 #endif /* KRB5 */
 
+static int
+already_succeeded(request_rec *r)
+{
+   if (ap_is_initial_req(r) || MK_AUTH_TYPE == NULL)
+      return 0;
+   if (strcmp(MK_AUTH_TYPE, "Negotiate") ||
+       (strcmp(MK_AUTH_TYPE, "Basic") && strchr(MK_USER, '@')))
+      return 1;
+   return 0;
+}
 
 static void
 note_kerb_auth_failure(request_rec *r, const kerb_auth_config *conf,
@@ -881,7 +1101,7 @@ note_kerb_auth_failure(request_rec *r, const kerb_auth_config *conf,
    /* XXX should the WWW-Authenticate header be cleared first? */
 #ifdef KRB5
    if (use_krb5 && conf->krb_method_gssapi)
-      ap_table_add(r->err_headers_out, "WWW-Authenticate", "GSS-Negotiate ");
+      ap_table_add(r->err_headers_out, "WWW-Authenticate", "Negotiate");
    if (use_krb5 && conf->krb_method_k5pass) {
       ap_table_add(r->err_headers_out, "WWW-Authenticate",
                    ap_pstrcat(r->pool, "Basic realm=\"", auth_name, "\"", NULL));
@@ -906,6 +1126,7 @@ int kerb_authenticate_user(request_rec *r)
    const char *type = NULL;
    int use_krb5 = 0, use_krb4 = 0;
    int ret;
+   static int last_return = HTTP_UNAUTHORIZED;
 
    /* get the type specified in .htaccess */
    type = ap_auth_type(r);
@@ -927,11 +1148,14 @@ int kerb_authenticate_user(request_rec *r)
    }
    auth_type = ap_getword_white(r->pool, &auth_line);
 
+   if (already_succeeded(r))
+      return last_return;
+
    ret = HTTP_UNAUTHORIZED;
 
 #ifdef KRB5
    if (use_krb5 && conf->krb_method_gssapi &&
-       strcasecmp(auth_type, "GSS-Negotiate") == 0) {
+       strcasecmp(auth_type, "Negotiate") == 0) {
       ret = authenticate_user_gss(r, conf, auth_line);
    } else if (use_krb5 && conf->krb_method_k5pass &&
              strcasecmp(auth_type, "Basic") == 0) {
@@ -948,6 +1172,7 @@ int kerb_authenticate_user(request_rec *r)
    if (ret == HTTP_UNAUTHORIZED)
       note_kerb_auth_failure(r, conf, use_krb4, use_krb5);
 
+   last_return = ret;
    return ret;
 }
 
@@ -978,8 +1203,17 @@ module MODULE_VAR_EXPORT auth_kerb_module = {
        NULL                            /* [ 1] post read_request handling    */
 };
 #else
+static int
+kerb_init_handler(apr_pool_t *p, apr_pool_t *plog,
+                 apr_pool_t *ptemp, server_rec *s)
+{
+   ap_add_version_component(p, "mod_auth_kerb/" MODAUTHKERB_VERSION);
+   return OK;
+}
+
 void kerb_register_hooks(apr_pool_t *p)
 {
+   ap_hook_post_config(kerb_init_handler, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_check_user_id(kerb_authenticate_user, NULL, NULL, APR_HOOK_MIDDLE);
 }